GaAs semiconductor technology provides transistor devices of the npn bipolar transistor and n-FET types. Circuit design and system functionality require p-type devices, especially pnp bipolar transistors or p-channel field-effect transistors, which are not provided in the GaAs technology up to now. With only n-type devices available in GaAs technology, other circuit concepts are applied at the expense of increased current consumption, larger occupied area and other shortcomings. Semiconductor circuits in silicon comprise both n-type and p-type devices, but this is not the preferred technology for power amplifiers, especially in industrial applications. Although the lacking p-type transistor components can be provided on external circuit components, a full integration of both types of transistors is desired also in GaAs technology.
Merged or stacked FET-HBT integration schemes, often called BiFET or BiHEMT and containing both HBT and FET or P-HEMT devices on a single GaAs substrate, are reported in the following papers from the CS MANTECH Conference 2007: William Peatman, Mohsen Shokrani, Boris Gedzberg, Wojciech Krystek, and Michael Trippe: “InGaP-Plus™: Advanced GaAs BiFET Technology and Applications”; T. Henderson, J. Middleton, J. Mahoney, S. Varma, T. Rivers, C. Jordan, and B. Avrit: “High-Performance BiHEMT HBT/E-D pHEMT Integration”; Todd D. Basso and Richard B. Brown: “A Complementary GaAs Microprocessor for Space Applications”; and Ravi Ramanathan, Mike Sun, Peter J. Zampardi, Andre G. Metzger, Vincent Ho, Cejun Wei, Peter Tran, Hongxiao Shao, Nick Cheng, Cristian Cismaru, Jiang Li, Shiaw Chang, Phil Thompson, Mark Kuhlman, Kenneth Weller: “Commercial Viability of a Merged HBT-FET (BiFET) Technology for GaAs Power Amplifiers”; C. K. Lin, T. C. Tsai, S. L. Yu, C. C. Chang, Y. T. Cho, J. C. Yuan, C. P. Ho, T. Y. Chou, J. H. Huang, M. C. Tu, and Y. C. Wang: “Monolithic Integration of E/D-mode pHEMT and InGaP HBT Technology on 150-mm GaAs Wafers”.